1) (2x + 4) / 4.5 = 1 7/9 / 0.01

First, we need to convert the mixed number 1 7/9 to an improper fraction:

1 7/9 = (9 * 1 + 7) / 9 = 16/9

Now we can rewrite the equation:

(2x + 4) / 4.5 = 16/9 / 0.01

To simplify further, we can divide both sides by 0.01:

((2x + 4) / 4.5) / 0.01 = 16/9

(2x + 4) / 4.5 / 0.01 = 16/9

((2x + 4) / 4.5) * (1/0.01) = 16/9

(2x + 4) / (4.5 * 0.01) = 16/9

(2x + 4) / 0.045 = 16/9

Now, we can solve for x by cross multiplying:

9(2x + 4) = 16(0.045)

18x + 36 = 0.72

18x = 0.72 - 36

18x = -35.28

x = -35.28 / 18

x = -1.96

2) 2.5/6 / 2/3 = 2.1 / x - 0.6

First, we need to simplify the left side of the equation:

(2.5/6) / (2/3) = 2.5/6 * 3/2

= 7.5 / 12

= 5/8

Now, we can rewrite the equation:

5/8 = 2.1 / x - 0.6

Now, we can cross multiply and solve for x:

5(x - 0.6) = 2.1(8)

5x - 3 = 16.8

5x = 19.8

x = 19.8 / 5

x = 3.96